dos33fsprogs/gr-sim/starfield.c

192 lines
3.3 KiB
C

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "gr-sim.h"
#define NUMSTARS 16
struct fixed_type {
char i;
unsigned char f;
};
struct star_type {
struct fixed_type x;
struct fixed_type y;
struct fixed_type z;
int color;
};
static void double_to_fixed(double d, struct fixed_type *f) {
int temp;
temp=d*256;
f->i=(temp>>8)&0xff;
f->f=temp&0xff;
}
#if 0
static void print_fixed(struct fixed_type *f) {
printf("%02X.%02X",f->i,f->f);
}
#endif
static void fixed_add(struct fixed_type *x, struct fixed_type *y, struct fixed_type *z) {
int carry;
short sum;
sum=(short)(x->f)+(short)(y->f);
if (sum>=256) carry=1;
else carry=0;
z->f=sum&0xff;
z->i=x->i+y->i+carry;
}
static double fixed_to_double(struct fixed_type *f) {
double d;
d=f->i;
d+=((double)(f->f))/256.0;
// printf("(%02x.%02x)=%lf\n",f->i,f->f,*d);
return d;
}
static struct star_type stars[NUMSTARS];
static int random_table[256];
static int random_pointer=0;
static void random_star(int i) {
/* -128 to 128 */
/* Should we xor? */
stars[i].x.i=random_table[random_pointer++];
if (random_pointer>255) random_pointer=0;
stars[i].x.f=random_table[random_pointer++];
if (random_pointer>255) random_pointer=0;
stars[i].y.i=random_table[random_pointer++];
if (random_pointer>255) random_pointer=0;
stars[i].y.f=random_table[random_pointer++];
if (random_pointer>255) random_pointer=0;
// double_to_fixed( (drand48()-0.5)*spreadx,&stars[i].x);
// double_to_fixed( (drand48()-0.5)*spready,&stars[i].y);
/* 0.1 to 16 */
stars[i].z.i=random_table[random_pointer++]/16;
if (random_pointer>255) random_pointer=0;
stars[i].z.f=0x1;
// double_to_fixed( ((drand48())*spreadz)+0.1,&stars[i].z);
// print_fixed(&stars[i].x);
// printf(",");
// print_fixed(&stars[i].y);
// printf(",");
// print_fixed(&stars[i].z);
// printf("\n");
// double_to_fixed((drand48()-0.5)*spreadx,&stars[i].x);
// double_to_fixed((drand48()-0.5)*spready,&stars[i].y);
// stars[i].z.i=spreadz;
}
int main(int argc, char **argv) {
int ch,i;
// int spreadx=256;
// int spready=256;
int spreadz=16;
struct fixed_type speedz;
for(i=0;i<256;i++) {
random_table[i]=rand()%256;
printf("%d\n",random_table[i]);
}
double_to_fixed(-0.25,&speedz);
grsim_init();
/* Should NUMSTARS be prime to help with randomness */
for(i=0;i<NUMSTARS;i++) {
random_star(i);
}
home();
gr();
while(1) {
gr();
/* Set color */
for(i=0;i<NUMSTARS;i++) {
if (stars[i].z.i<(spreadz/3)) stars[i].color=15;
else if (stars[i].z.i<(spreadz*2/3)) stars[i].color=13;
else stars[i].color=5;
}
/* draw stars */
for(i=0;i<NUMSTARS;i++) {
int tempx,tempy;
double dx,dy;
dx=fixed_to_double(&stars[i].x)/
fixed_to_double(&stars[i].z);
tempx=dx+20;
dy=fixed_to_double(&stars[i].y)/
fixed_to_double(&stars[i].z);
tempy=dy+20;
if ((tempx<0) || (tempy<0) || (tempx>=40) ||
(tempy>=40)) {
random_star(i);
}
else {
color_equals(stars[i].color);
basic_plot(tempx,tempy);
}
}
/* Move stars */
for(i=0;i<NUMSTARS;i++) {
fixed_add(&stars[i].z,&speedz,&stars[i].z);
}
grsim_update();
ch=grsim_input();
if (ch=='q') exit(0);
usleep(10000);
}
return 0;
}